A system management interrupt (SMI) is a nonmaskable external interrupt that operates independently from a processor's interrupt- and exception-handling mechanism and a local interrupt controller, such as an Intel advanced programmable interrupt controller (APIC). SMIs take precedence over other non-maskable and maskable interrupts. SMIs directed to a processing core indicate that a processing core is to transition to system management mode (SMM), which is a special-purpose operating mode provided for handling system-wide functions, such as power management, system hardware control, or proprietary OEM (Original Equipment Manufacturers)-designed code, for example.